Posted on by Wladimir Palant

Avast took an interesting approach when integrating their antivirus product with web browsers. Users are often hard to convince that Avast browser extensions are good for them and should be activated in their browser of choice. So Avast decided to bring out their own browser with the humble name Avast Secure Browser. Their products send a clear message: ditch your current browser and use Avast Secure Browser (or AVG Secure Browser as AVG users know it) which is better in all respects.

Avast Secure Browser is based on Chromium and its most noticeable difference are the numerous built-in browser extensions, usually not even visible in the list of installed extensions (meaning that they cannot be disabled by regular means). Avast Secure Browser has eleven custom extensions, AVG Secure Browser has eight. Now putting eleven extensions of questionable quality into your “secure” browser might not be the best idea. Today we’ll look at the remarkable Video Downloader extension which essentially allowed any website to take over the browser completely (CVE-2019-18893). An additional vulnerability then allowed it to take over your system as well (CVE-2019-18894). The first issue was resolved in Video Downloader 1.5, released at some point in October 2019. The second issue remains unresolved at the time of writing. Update (2020-01-13): Avast notified me that the second issue has been resolved in an update yesterday, I can confirm the application version not being vulnerable any more after an update.

Malicious actors coming through Avast software

Note: I did not finish my investigation of the other extensions which are part of the Avast Secure Browser. Given how deeply this product is compromised on another level, I did not feel that there was a point in making it more secure. In fact, I’m not going to write about the Avast Passwords issues I reported to Avast – nothing special here, yet another password manager that made several of the usual mistakes and put your data at risk.

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Posted on by Wladimir Palant

December last year has been an interesting month in Avast-land. After my investigation into Avast’s data collection practices didn’t attract any attention initially, Mozilla and Opera removed Avast’s browser extensions from their respective add-on stores immediately after I reported them. Google spent two weeks evaluating the issue but eventually did the same. The matter of Avast selling users’ data even attracted attention of high-level politicians.

Avast watching you while browsing the web

Avast’s official communication throughout that month was nothing short of amazing. I found it hard to believe that a company could keep denying any wrongdoing despite all the evidence to the contrary. Avast’s CEO Ondrej Vlcek even gave an interview to the Forbes magazine where he claimed that there was no privacy scandal here. Users clearly disagreed, and so did most journalists. But the company’s stance didn’t change: all the data collected is necessary to protect users, and selling it later without user’s agreement is completely unproblematic due to the data being “anonymized.”

So when on December 22nd they finally brought out updated versions of their extensions, I was very curious to see what they changed other than writing a usable privacy policy. The updates have been accepted by all browser vendors and, at the time of writing, all four extensions are available for Firefox and Chrome. The Opera Add-ons site currently lists three extensions, with Avast Online Security still missing.

Let’s say this much up front: the changes are far more extensive and far more convincing than I would have expected. While Chrome and Opera versions appear identical however, there are some additional changes in the Firefox version. That’s presumably to comply with stricter privacy requirements of the Mozilla Add-ons site.

Update (2020-01-10): Avast contacted me to clarify the situation. One piece of information stood out here: “we completely discontinued the practice of using any data from the browser extensions for any other purpose than the core security engine.” In other words, Avast isn’t merely doing the bare minimum required to comply with store policies, they completely give up collecting too much data via their browser extensions and they won’t share this data with anybody either. That’s a massive privacy improvement for any Avast users out there. The open question is whether this policy change also applies to the Avast SafePrice extension and Avast Secure Browser. I’ll update the post again once I have the answer. Update (2020-01-16): The quoted statement from Avast seemed unambiguous, yet further communication established that sharing data with Jumpshot is going to be opt-in functionality for users of the free antivirus application. It’s still an improvement of course but quite different from the initial statement. As to Avast SafePrice and Avast Secure Browser, improvements are expected here in future. Supposedly, the data collected by these was never used, a statement that is impossible to validate.

Just to be clear: with the large codebases and without any official information from Avast I might have overlooked some of the changes. On Firefox I looked at Avast Online Security 19.4.426, on Chrome at Avast Online Security 19.4.433 and on Opera at AVG Online Security 19.4.433.

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Posted on by Wladimir Palant

A while back we’ve seen how Avast monetizes their users. Today we have a much smaller fish to fry, largely because the Avira’s extensions in question aren’t installed by default and require explicit user action for the additional “protection.” So these have far fewer users, currently 400 thousands on Firefox and slightly above a million on Chrome according to official add-on store numbers. It doesn’t make their functionality any less problematic however.

That’s especially the case for Avira Browser Safety extension that Avira offers for Firefox and Opera. While the vendor’s homepage lists “Find the best deals on items you’re shopping for” as last feature in the list, the extension description in the add-on stores “forgets” to mention this monetization strategy. I’m not sure why the identical Chrome extension is called “Avira Safe Shopping” but at least here the users get some transparency.

Avira user interface offering Browser Safety extension as protection feature

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Posted on by Wladimir Palant

A month ago I wrote about Avast browser extensions being essentially spyware. While this article only names Avast Online Security and AVG Online Security extensions, the browser extensions Avast SafePrice and AVG SafePrice show the same behavior: they upload detailed browsing profiles of their users to uib.ff.avast.com. The amount of data collected here exceeds by far what would be considered necessary or appropriate even for the security extensions, for the shopping helpers this functionality isn’t justifiable at all.

Avast watching you while browsing the web

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Posted on by Wladimir Palant

Now that I’m done with Kaspersky, it’s time to look at some other antivirus software. Our guest today is McAfee Total Protection 16.0. Let’s say this up front: it’s nowhere near the mess we’ve seen with Kaspersky. It doesn’t break up your encrypted connections, and the web protection component is limited to the McAfee WebAdvisor browser extension. So the attack surface is quite manageable here. The extension also uses native messaging to communicate with the application, so we won’t see websites taking over this communication channel.

Of course, browser extensions claiming to protect you from online threats have some rather big shoes to fill. They have to be better than the browser’s built-in malware and phishing protection, not an easy task. In fact, McAfee WebAdvisor “blocks” malicious websites after they already started loading, this being not quite optimal but rather typical for this kind of extension. I also found three issues in the way McAfee WebAdvisor 6.0 was implemented which made its protection far less reliable than it should be.

Rusty WebAdvisor shield

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Posted on by Wladimir Palant

I’m discuss three more vulnerabilities in Kaspersky software such as Kaspersky Internet Security 2019 here, all exploitable by arbitrary websites. These allowed websites to uninstall browser extensions, track users across Private Browsing session or even different browsers and control some functionality of Kaspersky software. As of Patch F for 2020 products family and Patch I for 2019 products family all of these issues should be resolved.

Kaspersky functionality shattered

Note: This is the high-level overview. If you want all the technical details you can find them here. There are also older articles on Kaspersky vulnerabilities: Internal Kaspersky API exposed to websites and Kaspersky in the Middle - what could possibly go wrong?

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Posted on by Wladimir Palant

This will hopefully be my last article on vulnerabilities in Kaspersky products for a while. With one article on vulnerabilities introduced by interception of HTTPS connections and another on exposing internal APIs to web pages, what’s left in my queue are three vulnerabilities without any relation to each other.

Kaspersky functionality shattered

Note: Lots of technical details ahead. If you only want a high-level summary, there is one here.

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Posted on by Wladimir Palant

In December 2018 I discovered a series of vulnerabilities in Kaspersky software such as Kaspersky Internet Security 2019. Due to the way its Web Protection feature is implemented, internal application functionality can used by any website. It doesn’t matter whether you allowed Kaspersky Protection browser extension to be installed, Web Protection functionality is active regardless and exploitable.

Kaspersky's communication with the browser protected by an easy to find key

Note: This is the high-level overview. If you want all the technical details you can find them here.

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Posted on by Wladimir Palant

Kaspersky’s web protection feature will block ads and trackers, warn you about malicious search results and much more. The complication here: this functionality runs in the browser and needs to communicate with the main application. For this communication to be secure, an important question had to be answered: under which doormat does one put the keys to the kingdom?

Kaspersky's communication with the browser protected by an easy to find key

Note: Lots of technical details ahead. If you only want a high-level summary, there is one here.

This post sums up five vulnerabilities that I reported to Kaspersky. It is already more than enough ground to cover, so I had to leave unrelated vulnerabilities out. But don’t despair, there is a separate blog post discussing those.

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Posted on by Wladimir Palant

Are you one of the allegedly 400 million users of Avast antivirus products? Then I have bad news for you: you are likely being spied upon. The culprit is the Avast Online Security extension that these products urge you to install in your browser for maximum protection.

But even if you didn’t install Avast Online Security yourself, it doesn’t mean that you aren’t affected. This isn’t obvious but Avast Secure Browser has Avast Online Security installed by default. It is hidden from the extension listing and cannot be uninstalled by regular means, its functionality apparently considered an integral part of the browser. Avast products promote this browser heavily, and it will also be used automatically in “Banking Mode.” Given that Avast bought AVG a few years ago, there is also a mostly identical AVG Secure Browser with the built-in AVG Online Security extension.

Avast watching you while browsing the web

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